A backward error correction schemes such as Automatic Repeat Request (ARQ) and forward error correction (FEC) may be used in packed data communication systems. Some cellular communication systems and wireless local area network (WLAN) may use the above error correction schemes to transfer packed data over air links. A data packet used in the packed data communication system may be referred as a data block. The ARQ mechanism sends\receives Acknowledged (ACK)\Not Acknowledged (NACK) indications of data block decoding success in the receiver.
ARQ scheme may include retransmissions of data for transmission that have been received with corrupted data. Some ARQ schemes for example, Hybrid-ARQ (also known in the art as H-ARQ type m with one redundancy version) may involve retransmissions of a data block and combining copies of the data block at a receiver memory.
Another form of hybrid ARQ scheme, which may be known in the art as incremental redundancy (IR) or as H-ARQ type II or type III, may transmit additional information of negatively acknowledged data blocks. In the ARQ scheme, a decoder in the receiver may store at the receiver memory information from received transmissions of the data block The decoder may combine and decode available information related to the data block.
Accordingly, in the case that the quality of the air link is poor, the amount of retransmissions may be increased, and the receiver memory may not be able to store at least some of the received data blocks. Thus, error correction and/or decoding of the packed data may fail.
Thus, there is a continuing need for better ways to mitigate the above-described disadvantages.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.